Blood circulation through the body is essential for maintenance and growth of calls and tissues. Any condition that restricts blood flow can have mild to disastrous consequences. For example, when blood flow in the brain is impeded, stroke can result. Stroke is a medical affliction that has severe consequences for most people who suffer it. Stroke is classified into four types, two of which are caused by blood clots (ischaemic stroke) and two of which are caused by haemorrhage (haemorrhagic stroke). Cerebral thrombosis and cerebral embolism account for up to 80 percent of all strokes.
Treatment options for stroke are limited. For example, only tissue plasminogen activator (tPA) has been approved, by the United States Food and Drug Administration as a pharmaceutical therapeutic treatment for ischaemic stroke.
It has been shown that the use of ultrasound waves and the Doppler frequency shift can be used to monitor the flow of blood through vessels (eg. Tegeler and Ratanakorn, 1999). Apparatus have been developed to exploit the potential of ultrasound to locate the interface between tissue types in the body, in particular, in the head, using transcranial Doppler ultrasound technology (TCD). U.S. Pat. No. 4,817,621 described apparatus to locate reliably blood vessels in the brain and to determine blood flow through vessels in the head using TCD. The apparatus relied on the combination of two parallelogram-like linkage systems to support and locate an ultrasound transducer near the head of a patient to locate occluded blood vessels in the brain using TCD. More recently, it has been shown that monitoring of patients with TCD, in addition to treatment with tPA may increase the effectiveness of tPA in the treatment of ischaemic stroke (Alexandrov et al. 2004), using commonly available TCD devices and operators skilled in using the devices to locate occlusions.
Transcranial Doppler technology has been shown to be useful in the identification and treatment of small vessel knock (WO2004/103184) associated with small vessel occlusion leading to stroke. The treatment taught in WO2004/103184 requires significant effort by an operator to find and diagnose the occluded blood vessels characteristic of stroke. While it has been shown that currently available ultrasound transducers and systems may be used for monitoring occluded blood vessels in stroke might also be a beneficial treatment method alleviating the symptoms of stroke, the ability to use TCD as a therapeutic treatment is currently constrained by the ease of use of said currently available systems. Clinicians who have used currently available TCD systems have noted that vascular tests that require the use of said TCD systems are among the most difficult to perform (Alexandrov et al., 2004). The ability of clinicians to diagnose and treat stroke with the promising TCD ultrasound technology may be limited by the apparatus with which to diagnose and treat the condition. For example, the current method of identifying the presence of occlusions in brain blood vessels is a manual grading system, known as the thrombolysis in brain ischaemia (TIBI) flow grading system. One of the problems with a head cap or band mounted or any other body or head mounted automatic diagnostic or treatment ultrasound device is that stability of movement of the sensor with patient movement or simply device attachment slippage can affect measures and data integrity.
What is needed is an apparatus and method to more efficiently locate occluded blood vessels or vessels having restriction in the brain characteristic of stroke and to treat the occlusions or restrictions to alleviate the stroke symptoms.
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